Tube cleaner

ABSTRACT

A tube cleaner (42) for removing deposits from the inner wall of condenser and other types of tubes has scrapers (20) for contacting the inner wall of the tube. The scrapers (20) are adapted to contact the wall so as to form an angle of 90 degrees or less rearwards of the scrapers (20) when the cleaner travels through the tube, so as to achieve more effective cleaning. The scrapers (20) may consist of one or more split rings mounted in incomplete transverse channels (44) on a central core (32).

This invention relates to a tube cleaning device; more particularly,this invention relates to a device suited to cleaning condenser and heatexchanger tubes, inter alia.

For the sake of brevity, this invention will generally be described inconnection with tube cleaners for heat exchanger and condenser tubes.However, it is to be appreciated that the invention has application to awide variety of tubes and that the scope of the invention is not limitedto such cleaners.

Condenser and heat exchanger tubes are normally manufactured frommaterials such as brass, aluminium-brass, copper-nickel, titanium,stainless steel and carbon steel.

It is well known that tile operating efficiency of heat exchangers andcondensers in power plants is reduced and fluid flow is restricted whenthe condenser tubes become fouled by such deposits as scale, algae, mud,slime and the like. In addition, if tubes are not cleaned regularly,deposits may cause pitting or corrosion of the tubes, resulting in majordamage and shortened tube life.

Deposits in tubes can be classified loosely as two types: soft deposits,such as algae, mud and slime, and hard deposits, such as scale. The softdeposits may be loosened or even removed by using high pressure wateralone, but removal is most effective if high pressure water is combinedwith some abrasive action. Hard deposits need a positive abrasiveaction; water is useful mainly to flush out the hard deposits once theylave been scraped from the tube wall, and to remove acidic depositsfound under pitting peaks.

To clean the tubes, various systems have been devised. Many of theseinvolve the propulsion of a cleaning projectile through time tubes.Propulsion is effected by means of an air, water or air/water gun whichshoots the projectile through the tube. Over the years, time projectileshave included rubber scraper plugs, balls and brushes and may bepropelled through the tubes.

In recent years, more sophisticated propelled tube cleaners have beendevised. One such tube cleaner, designed for use with a water gun,comprises a metal core on which are mounted a series of spring-loadedmetal scraper blades. Each blade is designed to make contact with partof the arc of the tube wall's diameter, by forming an obtuse angle withtime wall. Time blades are fixed in position around the metal core sothat their arcs overlap and all the circumference of a tube wall isintended to be contacted by at least one blade as the cleaner progressesthrough the tube.

This cleaner is designed to remove obstructions and debris as well asall deposits, including soft deposits and hard scale from the tube wall.It will be appreciated that time cleaner has a certain degree of bodystrength and this is required in order to remove hard scale effectively.Material removed by the scraper blades is swept through the tube by thewater used to propel the cleaner.

This prior art cleaner may be reusable for up to 20 times; however,depending on the nature of the deposits, the life of the cleaner may bereduced to 8 to 10 uses. In addition, this cleaner suffers from thedisadvantage that the metal blades may corrode unless cared for in aproper manner. Further, the fit between the tube wall and the scraperblades must be a close one for the cleaner to operate efficiently. Thereis very little tolerance for variations in the diameter of the tube.Therefore, this cleaner is not adaptable for use with tubes which varyin size, even within a small range of gauge.

This can be a significant problem. Many tubes have a plastic or otherlining running from the inlet into the tube for a short way, to preventwater erosion of the tube. If the prior art tube cleaner referred toabove is chosen to fit the lined part of the tube, there may beinsufficient contact between the scraper blades and the unlined lengthof the tube to effect proper cleaning. On the other hand, if the tubecleaner is chosen to fit the unlined length of the tube, there will be atight fit between the cleaner and the lined part of the tube and use ofthe cleaner may damage the lining, especially in the case of plasticlinings.

In addition, many cleaners are not intended for use in other thanstraight tubes.

Another type of tube cleaner now available consists of a scrubber madeof semi-rigid plastic such as polyethylene and consists of a core bodyand a series of scraping discs integral therewith. This scrubber isdesigned for use with air and water guns: the scrubber channels thewater through apertures in the scrubber, so that deposits may beloosened and swept out of the tube. The scraping discs which aredesigned to meet the tube at an obtuse angle, are relatively flexibleand can adjust to the diameter of the tube. In a situation where theinlet and outlet of the tube is lined, as described above, theflexibility of the discs and the use of plastic rather than metal in thescraping discs means that there is little likelihood of damaging theplastic lining, while at the same time there is an adequate fit with theunlined part of the tube.

While each scrubber is relatively inexpensive and adaptable to be usedin tubes having a small variation in diameter, as indicated above, it isnecessary to use different sized scrubbers if there is a largervariation in diameter. In addition, the scrubber may have a short life,especially if hard deposits are frequently encountered.

The polyethylene scrubber suffers from a further disadvantage: somewater contains a significant amount of mineral salts and leaves stubbornscale on tubes. It has been found that the polyethylene scrubber hasinsufficient body strength to remove this.

Both the prior art cleaners described in detail above are vulnerable todamage if they hit a solid obstacle. The metal cleaners wear andriveting becomes loose, with the result that the cleaners areineffective after about 10 uses. The plastic scrubbers break and must bediscarded.

The above description relates to heat exchange and condenser tubes.However, there is a different type of problem encountered in the case ofsome other types of tubes, such as chiller sets for air conditioningplant. The tube bores in these situations are not always of constantdiameter. At present, it is common to use a brush driven by a flexiblecable to clean these tubes, the cable causing the brush to rotate as ittravels through the tube. However, these flexible brushes, whosebristles are dragged back against the wall of the tube during thecleaning operation, wear rapidly and require replacement frequently.

It is an aim of the present invention to provide a tube cleaner which,in particular embodiments, substantially overcomes or at leastalleviates some or all of the drawbacks presented by prior art tubecleaners and which incorporates other advantages not available withprior art cleaners.

The present invention is predicated upon the discovery that tubecleaning is far more effective if scraper blades or bristles contact theinner wall of the tube at an acute angle or in a perpendicular manner,rather than at an oblique angle as is the case with prior art cleaners.

Accordingly, the present invention provides a tube cleaner having atleast one scraper means for contacting an inner wall of a tube, thescraper means having one end mounted on or integral with a central coreand the other end adapted to contact the tube wall in a non-sealingmanner, characterised in that when the cleaner travels through the tube,said other end forms an angle of 90 degrees or less with the tube wallrearwards of said other end.

The scraper means may take many forms. One preferred embodiment will nowbe described. The or each scraper means is mounted on a central core andthe or each scraper means is capable of replacement without damage tothe core.

The core may be manufactured from any appropriate material, butpreferably is made from a material which provides sufficient bodystrength to enable the cleaner to scrape hard deposits such as scalefrom the tube wall. It is also preferred that the core is made from amaterial which will not bend or break but which will retain its shape,even after hitting an obstruction at speed. One such suitable materialis a plastic polymer, for example, some forms of polypropylene. Anotheris metal, such as steel. Others will be apparent to one skilled in theart, or will be apparent after suitable experimentation.

The diameter of the core may vary according to the diameter of the tubeto be cleaned. For example, the diameter of the core may range from 4.5mm to 63.5 mm or even more. However, as will be appreciated from thedescription below, it is possible to use one size of core in conjunctionwith suitably-sized scraper means, to clean a relatively wide range oftube dimensions.

The scraper means may be mounted on the core in any manner which permitsthe scraper to be effective in operation but replaceable withoutdamaging the core. There are advantages in being able to replace thescraper means without having to replace the core. For example, if one ormore scraper means becomes damaged or worn, each may be discarded infavour of a new scraper. In addition, the same core may be used fortubes of different gauges, by replacing the scraper means with othermeans of lesser or greater diameter.

In one form, the scraper means comprises a split ring of resilient butrelatively rigid material, mounted in a transverse channel in the core.If it is desired to replace the scraper means, for example because thescraper means has become worn or damaged, or so as to cater for a tubeof different gauge, the existing scraper is pried away from the core anda replacement is snapped on to the core. The split ring configurationhas the advantage that if the ring encounters an obstruction such as ascale build up, the pressure on the ring will cause the split to widen,which in turn will increase the diameter of the ring, thus enhancing thescraping action of ring. In addition, if the tube has an ovalcross-section, due to sagging or other causes, the split can narrow andthe ring may still pass through the tube.

For most applications, the tube cleaner of the invention in thisembodiment will include three or four scraper means mounted at intervalsalong the core. However, if it is desired that the tube cleaner cannegotiate bends in the tubes, time cleanser may be relatively short,with only one or two scraper means.

As to suitable material for the scraper means, this is preferably aplastic polymer. It is also contemplated that the scraper means may bemade from metal, such as stainless steel, bronze or other suitablematerial. The tube cleaner of the invention may have on the same corescraper means of different materials--for example, there may be fourscraper means, with the first being a plastic polymer, the second beingmetal, and so on. This form of the invention may have advantages inremoving deposits of a wide variety of types.

The scraper means preferably has a sharp edge which presents towards thefront of the tube cleaner when in use, so that there will be excellentabrasive action between the scraper means and the wall of the tube andhard deposits will be removed from the wall.

In cross-section, the scraper means may be rectangular, for example, ormay have the leading edge sharpened via a taper or arc.

This embodiment of the tube cleaner of the present invention preferablyhas openings to allow water to pass through the cleaner and to be forcedthrough apertures aimed at the tube wall, so as to loosen deposits,especially soft deposits and to assist flushing of loosened materialfrom the tube.

This may be achieved by having a core which is hollow throughout itslength but sealed (or substantially sealed) at the leading end. Eachscraper means is mounted in an external transverse groove on the core.In each groove are one, two, three or four apertures, each of whichcommunicates with the hollow bore in the core. (There need not be thesame number of apertures in each groove--for example, the groove closestto the leading end of the cleaner may have four apertures, while theothers may have only one or two. Each scraper means is fixed in itsgroove by a peg or other suitable means, and the scraper means aresuitably shaped, so that in successive grooves one aperture is availablefor the emission of water an such apertures are staggered with respectto each other. In each groove, preferably there is at least one apertureopposite the peg or other suitable means fixing the scraper in thegroove.

The tube cleaner of the invention may be caused to travel through thetube in various ways. Where the scraper means are mounted transverselyon a central core, the tube cleaner will normally be propelled throughthe tube by hydraulic or pneumatic means such as a water or air gun ofsufficient force. A combined hydraulic and pneumatic means may also beused. The gun required may need to be able to exert a force greater than400 psi to propel the tube cleaner.

Where the tube cleaner of tile invention is used in large-gauge tubes,such as calandria in the sugar refining industry, mains pressure watermay be substituted for the gun employed for heat exchanger and condensertubes. In this embodiment, the cleaner does not have openings to allowwater to pass through the cleaner, but incorporates a piston to assistpropulsion by means of the mains water pressure.

The invention will now be described in greater detail in connection withthe accompanying drawings, in which;

FIGS. 1A, 1B and 1C compare schematically the manner in which thescraper means of one embodiment of the tube cleaner of the invention andthe prior art scraper means contact the inner wall of a tube;

FIG. 2 represents a longitudinal sectional view of an embodiment of thetube cleaner of the invention;

FIG. 3 is a transverse sectional view taken along the lines 3--3 of FIG.2;

FIG. 4 is a transverse sectional view taken along the lines 4--4 of FIG.2;

FIG. 5 is a transverse sectional view taken along the lines 5--5 of FIG.2;

FIG. 6 is a longitudinal sectional view of a second embodiment of thetube cleaner of the invention;

FIG. 7 is a transverse half sectional view taken along the lines 7--7 ofFIG. 6;

FIG. 8 is a transverse sectional view taken along the lines 8--8 of FIG.6;

FIG. 9 is a transverse sectional view taken along the lines 9--9 of FIG.6;

FIG. 10 is a transverse sectional view taken along the lines 10--10 ofFIG. 6; and

FIG. 11 is a transverse sectional view taken along the lines 11--11 ofFIG. 6.

Referring first to FIG. 1A, scraper means 20 (attached to a central coreof a tube cleaner of the invention, not shown) contacts tube wall 22 atan acute angle x, which is substantially maintained when the tubecleaner travels through the tube in the direction of arrow 24.

FIG. 1B, bristle 26 of a tube cleaning brush, not shown, contacts tubewall 22 in an approximately perpendicular manner when the brush is atrest. However, when the brush travels through the tube in the directionof arrow 24, bristle 26 is forced rearwardly, to form an obtuse angle ywith the tube wall 22.

In FIG. 1C, blade 28 of a prior art scraper (not shown) contacts tubewall 22 at a right angle when the scraper is at rest. However, when thescraper is forced through the tube, blade 28 is bent rearwardly to forman obtuse angle z with tube wall 22.

Turning now to FIG. 2, tube cleaner 30 consists of a central core 32 andfour concentric scraper means 20. Core 32 also has a core head 34.Central aperture 36 in core 32 communicates with outlets 38 (seeespecially FIG. 3). When this tube cleaner is propelled through a tubefrom a water gun, water is forced through aperture 36 and outlets 38 toassist flushing of the tube.

As illustrated by FIGS. 4 and 5, scraper means 20 comprise blades 40,arranged so that each part of the inner circumference of tube wall 22will be contacted by a blade 40.

The embodiment of the tube cleaner 42 in FIGS. 6 to 11 has a centralcore 132 made of plastic polymer and incorporates four incompletetransverse channels 44, each terminating at tongue 146.

In this embodiment, the scraper means 20 consists of a split ring ofresilient but relatively rigid material (for example, a material whichis harder that polyethylene) mounted in each of transverse channels 44.For ease of illustration, only one split ring is shown (see FIG. 8).Tongue 146 nerves to maintain the split ring scraper means 120 inchannel 44 and to prevent undue rotation.

A portion only of split ring scraper means 120 is illustrated in FIG. 6,once again for clarity. It can be seen that forward edge 48 will form anacute angle with the tube wall (not shown).

Core 132 has a core head 34 and a central aperture 36 communicating wiltoutlets 38, not only in core head 34 but also in channels 44, one suchoutlet being located opposite each tongue 146. It is of course possibleto incorporate additional outlets 138 if desired.

It will be appreciated from the foregoing that the tube cleaner of thepresent invention may be capable of dealing with hard deposits as wellas soft, that it may be made in a form which will not bend or break oncollision with a solid obstruction, that it permits great flexibility asto the selection of scraper material and size and has economicaladvantages, and so represents a significant advance over the prior art.

Other forms of the invention and methods of use will be apparent to oneskilled in the art and the invention is not to be limited by thespecific examples referred to herein.

I claim:
 1. A tube cleaner comprising a central core having alongitudinal axis, and at least two radially extending scraper means forcontacting an inner wall of a tube, each said scraper means beingmounted on said central core and having a distal portion adapted tocontact the inner tube wall in a non-sealing manner, wherein saidcentral core has a hollow bore extending at least partially therethroughsubstantially parallel to said longitudinal axis, said hollow boreopening onto one end of said central core, said hollow bore furthercommunicating with at least one aperture extending in a generally radialdirection from said hollow bore, said at least one aperture opening ontoa peripheral surface of said central core for the emission of afluid,wherein when the tube cleaner travels through the tube, saidscraper means forms a forwardly directed angle greater than 90 degreeswith the tube wall forward of said scraper means, wherein each saidscraper means is replaceable without damaging said core, said distalportion of each said scraper means having a leading edge which faces thefront of the tube cleaner when in use, wherein at least twocircumferential channels are formed at intervals in said central core,wherein between two and four said scraper means are mounted in arespective circumferential channel.
 2. A tube cleaner as claimed inclaim 1, wherein said distal portion of said scraper means has a leadingedge facing towards the front of the tube cleaner when in use.
 3. A tubecleaner as claimed in claim 1, wherein each said scraper means comprisesa split ring.
 4. A tube cleaner as claimed in claim 3, wherein at leastone split ring is made of a plastic polymer.
 5. A tube cleaner asclaimed in claim 3, wherein at least one split ring is made of metal. 6.A tube cleaner as claimed in claim 3, wherein said split rings are madefrom different respective materials.
 7. A tube cleaner as claimed inclaim 3, wherein at least one of said apertures opens to an exterior atone of said circumferential channels.
 8. A tube cleaner as claimed inclaim 1, which is adapted to be propelled through the tube by one ofhydraulic means, pneumatic means and combined hydraulic/pneumatic means.9. A tube cleaner as claimed in claim 1, wherein said central core ismade from at least one of a plastic polymer and a metal.
 10. A scraperfor use on a tube cleaner having a core with a longitudinal axis, thescraper comprising:a radially extending annular-shaped member which isreplaceably mountable about at least a part of a circumference of thecore, wherein, when said annular-shaped member is mounted, said memberhas a distal periphery adapted to contact a tube wall in a non-sealingmanner and a leading edge portion that forms an angle greater than 90degrees relative to the tube wall in an operational direction of travel;wherein at least two said annular-shaped members are mountable on thecore in respective circumferential channels provided in the core,wherein each said annular-shaped member comprises a split ring, saidsplit rings being each made from different materials, respectively. 11.A scraper as claimed in claim 10, wherein said annular-shaped member ismade from at least one of a plastic polymer and a metal.
 12. A scraperfor use on a tube cleaner having a core with a longitudinal axis, thescraper comprising:a radially extending annular-shaped member which isreplaceably mountable about at least a part of a circumference of thecore, wherein, when said annular-shaped member is mounted, said memberhas a distal periphery adapted to contact a tube wall in a non-sealingmanner and a leading edge portion that forms an angle greater than 90degrees relative to the tube wall in an operational direction of travel;wherein the core has a circumferential channel formed at least partiallytherearound, wherein said annular-shaped member comprises a split ringadapted to be mounted in said circumferential channel.
 13. A scraper asclaimed in claim 12, wherein said annular-shaped member is made from atleast one of a plastic polymer and a metal.